G-STRING,
For slipping in Cessnas, the only advice is to read the relevant POH. The POH for some Cessnas - I believe it's only the later C172s, but don't quote me on that - advise against slipping with full flap. There is no such warning in the manuals for any of the aircraft I fly, and I regularly slip them without any problem.
As for the danger of spinning, if you keep the AoA below the critical angle, no there is no danger. Select a slightly lower nose attitude than you would if you weren't slipping. As a rough guide, keep the airspeed similar to what it would be for a normal approach, but bear in mind that the ASI may have errors during a slip, depending on the position of the pitot/static sensors.
FFF
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